Hydrogenation of organic compounds

ABSTRACT

NOVEL HYDROGENATION CATALYSTS ARE FORMED BY IMPREGNATING A SUITABLE SUPPORT MATERIAL WITH AN AQUEOUS SOLUTION OF A SALT OF A TRANSITION METAL; HEAT-TREATING THE IMPREGNATED SUPPORT AT A TEMPERATURE ABOVE 500*F. TO FORM CHEMICAL COMPLEXES ON THE SURFACE OF THE SUPPORT AND TO DRIVE OFF MOISTURE AND ABSORBED OXYGEN; ACTIVATING THE SURFACE COMPLEX BY CONTACTING THE IMPREGNATED SUPPORT WITH A SOLUTION ORGANOMETALLIC COMPOUND WHEREIN THE METAL CONSTITUENT IS SELECTED FROM GROUPS I, II AND III OF THE PERIODIC CHART OF THE ELEMENTS, AND THEREAFTER TREATING THE ACTIVATED SUPPORT METERIAL IN THE PRESENCE OF A GASEOUS STREAM CONTAINING HYDROGEN AT A TEMPERATURE OF AT LEAST 300*F. TO FORM A HIGHLY STABLE HETEROGENEOUS CATALYST. THE NOVEL SUPPORTED CATALYSTS OF THE INSTANT INVENTION HAVE BEEN FOUND TO BE HIGHLY ACTIVE FOR THE HYDROGENATION OF ORGANIC COMPOUNDS UNDER EXTREMELY MILD CONDITIONS.

United States Patent 3,711,423 HYDROGENATION OF ORGANIC COMPOUNDS JosephK. Mertzweiller and Horace M; Teuney, Baton Rouge, La., assignors toEsso Research and Engineering Company No Drawing. Continuation-impart ofapplication Ser. No. 674,098, Oct. 10, 1967. This application Nov. 28,1969, Ser. No. 880,933 The portion of the term of the patent subsequentto July 18, 1989, has been disclaimed Int. Cl. C07g /02 U.S. Cl. 25243121 Claims ABSTRACT OF THE DISCLOSURE Novel hydrogenation catalysts areformed by impregnating a suitable support material with an aqueoussolution of a salt of a transition metal; heat-treating the impregnatedsupport at a temperature above 500 F. to form chemical complexes on thesurface of the support and to drive off moisture and absorbed oxygen;activating the surface complex by contacting the impregnated supportwith a soluble organometallic compound wherein the metal constituent isselected from Groups I, II and III of the Periodic Chart of theElements, and thereafter treating the activated support material in thepresence of a gaseous stream containing hydrogen at a temperature of atleast 300 F. to form a highly stable heterogeneous catalyst. The novelsupported catalysts of the instant invention have been found to behighly active for the hydrogenation of organic compounds under extremelymild conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is acontinuation-in-part of US. 'Ser. No. 674,098, filed Oct. 10, 1967 nowabandoned.

BACKGROUND OF THE INVENTION This invention relates to a new and usefulprocess for the preparation of high activity catalysts suitable forreactions between hydrogen and hydrocarbons and particularly for thehydrogenation, or hydrogen addition, to organic compounds containingnitrile groups, carbonyl groups, aromatic, acetylenic or olefiniclinkages. It is also concerned with the novel catalysts so produced, asWell as the processes for using these catalysts.

More particularly, this invention relates to impregnating a suitablesupport, as hereinafter defined, with a transition metal and thereaftertreating the supported catalyst with an organometallic compound undersuch conditions as to effect a chemical bonding of said metals to thesupport. Specifically, this invention relates to impregnating a suitablesupport material with a transition metal; heattreating the impregnatedsupport at a temperature of at least 500 F. to drive off moisture andabsorbed oxygen; activating the surface complex with an organometalliccompound and thereafter treating the activated species in the presenceof a gaseous stream containing hydrogen under critically definedconditions in order to form the highly active, stable hydrogenationcatalyst of the instant invention. This final step which comprisestreating the activated supported catalyst in the presence of hydrogenunder critically defined conditions is termed fixation ice and iscritically important in preparing completely heterogeneous catalystspossessing extremely high activity and stability.

DESCRIPTION OF THE PRIOR ART Various heavy metals, especially transitionmetals, have been previously described as useful for conductingcatalytic reactions. Hydrogenation catalysts have included solid metals,slurries of metals, and metals dispersed on supports. Solid metalcatalyst had been prepared by contacting oxides of the desired metalwith reducing gases, e.g., carbon monoxide, or hydrogen, or both.Slurries suitable as catalyst have been prepared by contacting anhydroussolutions of organometallic compounds of the desired metal withorganoaluminum compounds, these being brought together to form slurriedcatalysts. Metals have been provided on supports by impregnation ofsupport with anhydrous solutions of the salts of the desired metal, thisbeing found by reduction of the salts to produce deposition of metallicmetal.

In Canadian Pat. 697,780, which issued Nov. 10, 1964, methods aredescribed for improving the activity of cobalt and for convertingcertain inactive metals, i.e., manganese and molybdenum, into activehydrogenation catalysts. In typical reactions, slurried catalyticmixtures are produced by forming anhydrous solutions of soaps of thedesired metal, and the desired organometallic reducing agent, and thencontacting the two solutions together to form catalytic reactionmixtures, In accordance with one of the methods, a support isimpregnated by contact with anhydrous or nonaqueous solution of a soapof the desired metal, and with an organometallic reducing agent, such asorganoaluminum compound, to produce a loosely supported reaction productmixture of dispersed metals. In other techniques, supports areimpregnated with soaps of the desired metal, and the support thencontacted with a solution of the organometallic reducing agent toproduce supported catalytic mixtures.

While these catalysts are moderately active hydrogenation catalysts,there are nonetheless a number of disadvantages associated with theiruse. For one thing, the materials, in all the phases of their use arehighly pyrophoric and the slurries must be formed in an oxygenfreeatmosphere. Also, the catalytic materials formed are highly pyrophoric.Thus, the catalytic product of the reaction is an insoluble pyrophoricsolid which is highly reactive whether in slurry or supported form.Moreover, the material used in forming the catalysts are quiteexpensive, to say nothing of the cost involved, due to the extraprecautions which must be taken in handling the materials. Furthermore,the organic solvents which are used are highly flammable.

In US. Pat. 3,415,759 there is disclosed a method for preparing ahydrogenation catalyst by depositing cobalt carboxylate on adiatomaceous earth support and heating the supported cobalt carboxylateat a temperature between about and C. and thereafter reacting the thusheat-treated product with an aluminum alkyl. However, when temperaturesmaterially above about 160 C. are employed to dry the catalysts, thecatalyst becomes progressively deactivated, particularly insofar as thehydrogenation of high molecular weight compounds are concerned 3 SUMMARYOF THE INVENTION It has now been discovered that novel hydrogenationcatalysts exhibiting unusually high activity and stability may beprepared by impregnating a suitable support material, as hereinafterdefined, with an aqueous solution of a salt of a transition metal;heat-treating the impregnated support at a temperature of at least about500 F. to form chemical complexes on the surface of the support and todrive oif moisture and absorbed oxygen; activating the surface complexby contacting the impregnated supports with a soluble organometalliccompound wherein the metal constituent is selected from Groups I, II andIII of the Periodic Chart of the Elements, and thereafter treating theactivated support material in the presence of a gaseous streamcontaining hydrogen at a temperature of at least 300 F. The presentinvention is based on the discovery that a highly tenacious chemicalbonding can be formed between the surface of certain types of supportsand the transition metals and the metallic constituent of the solubleorganometallic compound when the metals are applied to the supportsunder the sequence and critically defined conditions of the instantinvention. In the sequence of process steps, a supporting materialhaving a surface area of at least 5 square meters per gram andcontaining at least 0.1 millimoles of hydroxyl groups per gram ofsupport is first impregnated with a water-soluble species of atransition metal, preferably a Group IB, IV-B, V-B, VII-B or Group VIIImetal. Water has been found particularly suitable for the application ofthe Group I-B, IVB, V-B, VIB, VII-B or Group VIII metals to the supportby contacting or immersing the support in an aqueous solution of a saltof the desired metal. Suitably, the support is impregnated with fromabout 0.1 to about metal, and preferably from about 2 to about 10%metal, based on the total weight of the deposited metal and support.

The impregnated support is then preconditioned by heating theimpregnated support at a temperature of at least about 500 F. in orderto drive off moisture and absorbedoxygen from the catalyst surface. Thepreconditioned catalyst is then activated by contacting the impregnatedsupports with a soluble organometallic compound wherein the metallicconstituent is selected from Group I, II and III of the Periodic Chartof the Elements and wherein the metallic constituent has an atomicnumber of from 3 to 50. Preferably, the organic constituent of theorganometallic compound are alkyl groups, particularly linear alkylgroups having from 1 to about 12 carbon atoms. Only the organometalliccompounds of Groups I, II and III which are soluble in hydrocarbon orsoluble in OR complex with ethers are suitable for the method of thisinvention. These are the organometallic species which are characterizedby predominantly covalent bonding between the metal and the alkyl and/or hydride groups. The preferred metallic constituent of theorganometallic compound is aluminum.

Thereafter, the activated supported material is treated by heating theactivated supported material at a temperature of at least 300 F. in thepresence of a gaseous stream containing hydrogen. Preferably, theactivated supported material is treated in the presence of hydrogen at atemperature above 800 F. and more preferably at a temperature in therange of from about 800 to about 1200 F. for a period of time in therange of from about 1 to about 100 hours. Surprisingly, it has beenfound that under these high severity conditions, i.e. treating theactivated supported catalyst at a temperature above 800 and up to about1200 F. in the presence of hydrogen, the activity of these catalysts isnot significantly decreased and, in fact, generally increases asthe'treating severity is increased. 1 1

While the exact nature of the mechanism is not known and, though theapplicants do not wish to be'bound by a specific theory or mechanism,there are certain things which are known to occur in the formation ofthese catalysts. When'a suitable" support has been impregnated-with atransition metal and heat-treated at a temperature of at least 500 F.,there is believed to exist a chemical bonding between the surface of thesupport and the species of the transition metal. This interaction isbelieved to occur between the acid sites on the support surface and thetransition metal salt. Evidence of such interaction is obtained when,for example, iron is employed as the transition metal and is impregnatedon a suitable support and heat-treated at a temperature of 500 F. inaccordance with the practice of the instant invention, and examined byMossbauer spectroscopy. Such an examination reveals that essentially alli.e. 99+% of the iron is in the +3 valence state and the Mossbauerpattern corresponds to no known oxide of iron nor to the iron saltemployed in impregnating the suitable supporting material. Consequently,this interaction or chemical bonding between the support and thetransition metal is believedto be responsible for the difficulty inreducing such a supported catalyst to metallic iron by treatment withhydrogen. For example, under conditions of 1 atmosphere hydrogenpressure'at a temperature of about 100 F., virtually all the iron isreduced to the +2 valence state, i.e. an inactive catalyst while littleor no metallic iron is formed. I

However, when the heat-treated impregnated support is treated with anexcess organometallic compound, for example, triethylaluminum, it isbelieved that the bond between the iron and the support is reduced bythe organometallic compound with the organometallic, i.e. metal alkylfragment being bonded to the support and replacing the reduced iron.Consequently, when the activated supported catalyst is then treated inthe presence of hydrogen under increasing severity conditions, tworeactions are believed to occur: (1) further reduction of the transitionmetal species to a lower valence species or tothefnascent metal state,and (2) simultaneous removal of the functional groups, i.e., alkyl andhydride groups from the metal alkyl fragments resulting in bondingbetween the alkyl metal and the transition metal. The above-describedreactions can be visualized as follows:

SupportaO-Q wherein M-X represents the transition metal salt impregnatedupon a suitable support, as hereinafter defined, by aqueous solution; Mthus representing the transition metal; where Q represents a Group I, IIor III metal and R represents the organic constituent of theorganornetallic compound and wherein n is equal to the valence state ofQ.

The free radical R resulting from Equation 2 must stabilize itself bycombination or disproportionation. When R is an ethyl radical, thecombination product is n-butane and the disproportionation products areethylene plus ethane. The gas liberated when these catalysts are treatedwith an organometallic compound, i.e. triethyl aluminum is predominantlyethane but containing appreciable amounts of ethylene and n-butane.Evidence for reactions (4) and (5) has been obtained by treating typicalgamma alumina supports with triethyl aluminum (no transition metalpresent) and analyzing the gases liberated when the treated alumina isheated at temperatures of 4001200 F. Reaction (6) represents bondingbetween a radical resulting from thermal decomposition of the Q metalhydride and an electron (probably a d-electron) supplied by thetransition metal in a reduced valence state.

While the exact nature of this bonding is unknown, it is believed thatthe productof reaction (6) which is believed to be a close approximationto the active sites of these catalysts, is a stable bond which accountsfor the increased activity and inhibition of crystallite growth on thesurface of the catalyst when the catalysts are subjected to hightemperatures in the presence of hydrogen. Closely related configurationssuch as:

/ Support can easily be formed from the product of reaction (5) to givethe iron a +2 valence state which has been observed in several cases forthese catalyst systems by Mossbauer and magnetic susceptibility.

As disclosed above, a critical feature of the instant invention is theconditions under which the activated supported catalyst is treated witha gaseous stream containing hydrogen. In terms of the mechanismdisclosed above, this fixation treatment is believed to favor thecompletion of reactions (3), (4), (5) and (6). In this manner catalystsseveral orders of magnitude more active and more stable than thosedescribed in prior art processes are obtained.

Thus, it is believed that the applicants have discovered a new route toa valuable and novel heterogeneous catalyst which is believed to involvechemical bonding between the support, transition metal and metallicconstituent of the organometallic reducing agent which allows for ahighly active catalyst which is stable under high severity conditions.

The selection of a suitable support material upon which the transitionmetal is impregnated is an essential feature of the instant invention.Suitable supports are those having a reasonable surface area and asufiicient concentration of hydroxyl groups on the surface, whichhydroxyl groups are capable of reacting with an organometallic compound,i.e. QR, or QR X Where Q represents a Group I, II or III metal, Rrepresents the organic constituent i.e. an alkyl group of theorganometallic compound or hydrogen, and wherein X equals a halogen, inorder to eliminate the RH species and attach the QR,, species to supportsurface through the oxygen atom of the original hydroxyl group.Properties and suitability of supports can be characterized in terms ofsurface area and their hydroxyl content measured by reaction with anorganometallic i.e. QR compound in the absence of a transition metal.

Those supports most suited to the instant invention include the oxidesof Groups II, III and IV of the Periodic Chart of the Elements which canbe prepared with surface areas in excess of 5 square meters per gram andwherein the hydroxyl content of the support is at least 0.1 millimole ofhydroxyl groups per gram of support. The oxides of Groups II, III and IVhaving a surface area in excess of 50 square meters per gram andcontaining a hydroxyl group content of at least 0.2 millimole ofhydroxyl groups per gram of support, determined by reaction of thesupport with the organometallic compound in the absence of thetransition metal are preferred. Aluminum oxide having a surface area ofabove about square meters per gram and a hydroxyl content of at least 1millimole per gram is the most preferred supporting material of theinstant invention. Additional, nonlimiting examples of suitablesupporting materials include magnesium oxide, zinc oxide, titaniumoxide, provided they have the necessary surface areas and reactivehydroxyl group content as described above. Any types of supports, whilepossessing the desired surface area, may or may not have the desiredreactive hydroxyl group content. Nevertheless, some such supports, forexample, activated carbon, can be enhanced in hydroxyl group content bytreatment with air or an air-steam mixture at moderate temperatures,i.e. below about 1000 F. in order to form a suitable support for thecatalyst of the instant invention. Other well-known supports, such assilica, have a suflicient surface area but may lack the necessaryconcentration of reactive hydroxyl groups and are not suitable.Silica-alumina supports, having the necessary hydroxyl groupconcentrations are effective supports and may also be employed in thepractice of the invention.

The supported catalyst of the instant invention may be prepared by anymeans conventionally used for the preparation of a supported catalyst,e.g. by impregnating the support or by precipitation in the presence ofthe support or by coprecipitation with the supporting material. Waterhas been found to be particularly suitable for the application of thetransition metal salt to the supporting materials. Preferably, thesupport is first impregnated with a water-soluble species of thetransition metal salt by contacting or immersing the support in anaqueous solution of the salt of the desired metal. Preferably, thesupport is impregnated with from about 0.1% to about 30% equivalenttransition metals; and preferably from about 1% to about 10% equivalenttransition metal, based on the total weight of the deposited equivalentmetal and support. The optimum concentration of transition metal on thesupport will depend on the nature of the transition metal and on thesurface area and hydroxyl content of the support. For example, when apure activated alumina having a surface area of about 200 square metersper gram and a hydroxyl content of about 1.2 millimoles per gram isemployed as the supporting material, and when iron is employed as thetransition metal, the optimum concentration of iron is about 0.6millimole of iron per gram support. With noble metals, for example muchlower concentration in the range of 0.1% to 1% are employed. The optimumconcentration for other transition metals which results in the highlyactive, stable catalysts of the instance invention are not known withexactitude because of the many and varied supports which can be employedherein. Nevertheless, it is believed that one skilled in the art canreadily determine these concentrations in view of the fact that they arewithin the preferred concentration ranges as described above.

The use of water to effect the chemical bonding is particularlyimportant in the impregnation of the supports with salts of the desiredtransition metal. Even ironhas produced an exceptionally active catalystwhen applied to the support in the form of salts dissolved in aqueoussolution. In fact, catalysts derived from aqueous solutions of ironsalts have even proved highly effective for the hydrogenation ofaromatic nucleus and carbonyl groups of organic compound, i.e. aldehydesand ketones.

The transition metals which can be employed in the practice of theinstant invention include the Group I-B, IV-B, V-B, VI-B, VII-B, andGroup VIII metals. Preferably, the transition metals which can beemployed in the practice of the instant invention include iron, cobalt,nickel, platinum, tungsten, chromium, vanadium, molybdenum, rheniummanganese, titanium, zirconium, palladium, rhodium, copper, silver andgold. The most preferred transition metals include iron, cobalt andnickel, platinum, tungsten, chromium, molybdenum, vanadium, rhenium andcopper. Nonlimiting examples of sales which can be employed for theapplication of these' metals to these supports include the halides,sulfates, nitrates, form- -ates, acetates, propionates, molybdate,vanadate's, chromates, dichromates, tungstates, manganates, titanates,zirconates, rhenates, perhenates and the like'. Water soluble acids suchas penrhenic acid may also be employed. These various transition metalsdescribed above may be used alone or in combination.

The impregnated support in powder or granular form, is then treated byestablishing time-temperature relationships suitable to produce achemical change on the surface of the support and remove water andabsorbed oxygen. Suitably, the impregnated support can be heated in air,in an inert atmosphere or in vacuum, e.g. to 29 inches of vacuum at atemperature of at least about 500 F. preferably 600 to 1500 F. and morepreferably from about 600 to about 1000 F. It is a critical feature, inorder to form the more highly active and stable catalyst of the instantinvention, to heat the impregnated support at a temperature above 500 F.for a period of time in the range of about 0.5 to about 4 hours andpreferably from about 1 to 2 hours. While the heat-treatment may beperformed in air or an oxygen atmosphere, it must then be followed by aperiod in an inert atmosphere in order to remove the adsorbed oxygen. Inaddition to the removal of oxygen and moisture, other importantreactions occur during this heat-treatment, as described above, in orderto render the transition metal in a form more amenable to the subsequentreaction with the organometallic compounds.

In an alternative embodiment, the impregnation and heat-treating stepscan be conducted in multiple stages. For example, the support can beimpregnated and then dried or partially dried, at low temperature. Thesupport can then be reimpregnated and again dried or partially dried.The heat treatment per se may be conducted in multiple stages, ifdesired. The impregnated support, to facilitate handling, can thus besubjected to a first rather mild heat treatment to dry the support andthen, in a second step, to a more severe treatment to produce thedesired chemical change at the surface of this support. Supportedcatalysts, such as are supplied by the commercial, catalystmanufacturers, e.g. iron, cobalt and/ or nickel, alone or in combinationwith other metals such as molybdenum, tungsten, or the like are alsoamenable to such treatments to transform them to highly activecatalysts.

The then impregnated, heat-treated support is activated by treatmentwith an organometallic compound, suitably a hydrocarbon solution of anorganometallic compound, or a hydrocarbon soluble organometalliccompound, a metallic constituent of which is selected from Groups I, IIand III of the Periodic Chart of the Elements as in Fisher ScientificCompany Copyright 1952. Preferably, the organometallic compounds includethose having the formula: QR wherein Q is equal to the metallicconstituent and is selected from Groups LA, II and III-A having anatomic number of from 3 to 50, n is the valence state of Q and whereini1 is the organic constituent and is selected from the group consistingof hydrogen or same or diiferent, substituted or unsubstituted saturatedor unsaturated alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl groupscontaining up to about 20 carbon atoms. Representative, nonlirnitingexamples of the organic constituents, i.e. 'R include, but are notlimited to methyl, ethyl, n-propyl, isopropyl, isobutyl, secondarybutyl, tertiary butyl, n-amyl, iso-amyl, heptyl, n-octyl, n-dodecyl andthe like; Z-butyl, Z-methyl-Z-butyl, and the like; cyclopentylmethyl,cyclohexylethyl, cyclohexyl-propyl and the like; Z-phenylethyl, Z-phenylpropyl, Z-naphlthylethyl, methylnaphthoethyi and the like; cyclopentyl,cyclohexyl, 2,2,1-bicycloheptyl and the like; methylcyclopentyl,dimethylcyclopentyl, ethylcyclopentyl, methylcyclohexyl,dimethylcyclohexyl, 5- cyclopentadienyl and the like; phenylcyclopentyl,and the like, phenyl, tolyl, ethylphenyl, Xylenyl naphthyl,cyclohexylphenyl and the like. The more preferred metallic constituentof the organic metallic compound i.e. Q is selected from the groupconsisting of lithium, magnesium, beryllium, zinc, cadmium, mercury,boron aluminum, gallium and indium. In addition, organometalliccompounds having the formula QR X may be employed as the organometalliccompound of the instant invention where Q and R are identical to the Qand R having been previously described, X is a halogen, and n and m areintegers ranging from 1 to 3, the summation equal to the valence of Q.

The most preferred organometallic activating agents are the tri-alkylsubstituted products of aluminum and the dialkyl halides of aluminum,particularly those containing alkyl groups having from one to about 6carbon atoms, especially the linear alkyl groups. Exemplary of suchcompounds, which contain up to about 18 carbon atoms in the molecule,are trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum,tri-isobutyl aluminum, diethyl aluminum hydride, diethyl aluminumchloride, diethyl aluminum fluoride and the like. Certain volatile orhydrocarbon-soluble hydrides, for example, the various known hydrides orboron, are also suitable activating agents as well as are the Grignardreagents.

The treatment of the supported, heat-treated catalyst with theorganometallic compound can be carried out with pure or diluted metalalkyl compounds in the liquid or vapor phase. Hydrocarbon diluents ofthe parafiinic, cyclo-paraflinic or aromatic types are entirelysuitable. The metal alkyl compound may be present in concentrations of5% to 50% in the diluent. A solution of about i 20% aluminum triethyl ina parafiinic diluent is a preferred activation system. The activationreaction is quite exothermic and it may be desirable to remove the heatof activation. The temperature during the activation step, which ismaintained in the range of from about 0 F. to about 500 F., preferablyfrom about F. to about 200 F. Considerable gas liberation occurs duringactivation and these gases are normally vented from the system. Theactivation is allowed to proceed until reaction is no longer observed,generally 0.5 hr. to 2 hrs. in contact with at least some excess ofmetal alkyl compound.

The treatment of the activated support material in order to obtain themost active and stable catalysts referred to above as the fixation stepis a critical feature of the instant invention. After the supportedcatalyst has been activated with the organometallic reducing agent, itis essential that the supported catalyst be treated in the presence of agaseous stream containing hydrogen at a temperature of at least 300 F.in order to form the highly active, stable, novel heterogeneous catalystof the instant invention. Preferably, the supported activated catalystis treated in the presence of hydrogen at a temperature in the range offrom about 300 F. to about 1200 F., more preferably from about 400 F. toabout 1200 F. and still more preferably between about 800, F. and 1200F. It is essential that this fixation treatment he conducted in thepresence of a' gaseous stream containing hydrogen. This fixationtreatment, can be carried out in the presence of inert gases such asnitrogen, helium, argon, and the like in view of the fact that hydrogenis formed in situ when these inert gases are employed. Necessarily,however, the fixation in the presence of such inert gases as nitrogen,helium, and argon will result in catalysts of lower activity than whenthe fixation step of the activated support catalyst is conducted totallyin the presence of a hydrogen gas.

Although nitrogen is normally considered an inert gas, there is evidencethat it may not be truly inert when present in the fixation of thesecatalyst systems. There is some evidence that gaseous nitrogen may reactwith the transition metal species at elevated temperatures. Suchreaction which may form nitrides of the metals are obviouslyundesirable. Therefore, it is preferred that the fixation step beconducted at the above critical temperatures in the presence of agaseous stream containing or resulting in the formation in the reactionzone of from about to 100% hydrogen and more preferably from about 75 toabout 100% hydrogen. Most preferably, the fixation under theabove-described critical temperature conditions is conducted totally inthe presence of a hydrogen atmosphere. As described above, it isbelieved that the function of hydrogen during the fixation step when thesupported activated catalyst is treated under the critical temperaturelimitation described above, is to fix the catalyst in a stableheterogeneous form and to further reduce the transition metal compoundto a valence state to which it can more readily and completely react themetallic portion of the organometallic compound.

The fixation of the supported activated catalyst in the presence of ahydrogen gas under the above-described critical conditions is usuallyconducted over a period of time varying between about 1 to about 100hours, generally less time being required at higher temperatures. Asdescribed above, it is quite surprising that under optimum conditions asdescribed above, it can be shown that the activity of the catalysts ofthe instant invention increases as the length of time in which thesupported activated catalyst is being treated in the presence ofhydrogen at high temperatures, e.g. 800-l200 F. increases. This, again,is believed to be due to the fact that the instant invention results incompletion of a series of reactions leading to a chemical bondingbetween the surface of the support and the transition metal and metalconstituent of the organometallic compound such that these metals arenot free to migrate on the surface of the catalyst and grow largecrystallites. The formation of large crystallites in conventionalsupported catalyst is generally accepted as an important mode ofcatalyst deactivation. Thus, the catalysts of the instant invention arehighly active at extremely mild hydrogenation conditions as well asexhibiting unusual stability at high severity conditions.

The fixation in the presence of hydrogen under the above-describedtemperature conditions can also be influenced by the hydrogen pressureat which such a treatment is conducted. Generally, atmospheric or nearatmospheric pressure, from about 0.5 to about 1.5 atmospheres isemployed. However, the hydrogen partial pressure may be increased in thereaction zone up to 100 atmospheres or greater. The hydrogen partialpressure will generally decrease the time-temperature requirements forforming the chemical bonding between the supports at a transition metaland metallic portion of the organometallic compounds.

The so-treated catalysts are then ready for contact with hydrogen orhydrogen-containing gases, a suitable reaction system for producinghydrogenation (or dehydrogenation) reactions. Olefins, whether singularor multiple linkage compounds, aliphatic or cyclic, and containing 2 toabout 50 carbon atoms have been readily hydrogenated to parafiins, andaromatic compounds containing from 6 to about 50 carbon atoms, and morepreferably from about 6 to about 30 carbon atoms havebeen saturated toproduce the corresponding cycloalkane. Acetylenic compounds, whethersingular or multiple linkage, aliphatic or cyclic in containing fromabout 2 to about 10 carbon atoms can also be hydrogenated by thecatalyst of the instant invention. In fact, catalyst formed by theimpregnation of the supports with aqueous salts of cobalt, and iron haveproven highly satisfactory despite the normally low activity attributedto cobalt and the even lower activity attributed to iron for producinghydrogenation reactions.

The catalysts can be utilized as slurries or as fixed beds, movable bedsand fluidized beds, in liquid phase or vapor phase, in batch, continuousor staged operations. Hydrogenation reactions can be carried out atremarkably low temperature and pressures as contrasted with the moreconventional catalysts, whether the reaction is conducted in liquidphase or vapor phase. Hydrogenation reactions are generally conducted attemperatures ranging from about 0 !F. to about 1000 F., and preferablyat temperatures ranging from about F. to about 500 F. The reactions canbe conducted at lower than atmospheric pressures or at supra atmosphericpressures, but generally pressures ranging from as low as about 1atmosphere to about 500 atmospheres can be employed. Preferably,however, pressures ranging from about 1 atmosphere to about 50atmospheres are employed in conducting the reactions.

These catalysts are suitable for carrying out hydrogenation reactions insystems designed to handle high heats of reaction and severe contactingproblems, without substantial deterioration and separation of catalystfrom the support. This is due in large part to the high stability andactivity of these catalysts, by virtue of .which hydrogenation reactionscan be conducted at very low hydrogen partial pressures ranging as lowas from about 1 to about 200 atmospheres.

When it is desired to carry hydrogenation reactions essentially tocompletion, an excess of hydrogen over the stoichiometric requirement isused. This excess may vary from a few percent to several hundred or evenseveral thousand percent. In the latter cases, the excess hydrogen isseparated and recycled to the system. When it is desired to carry outpartial hydrogenations, the reaction can be controlled on the basis ofhydrogen concentration, e.g., mol ratio of H to feed, or reactionkinetics, e.g., using an excess of hydrogen and controlling re-ZIIiCIflOH by time, temperature, H partial pressure and the These andother features of the invention will be understood by reference to thefollowing illustrative examples.

Example 1 These examples (A through F, Table I) illustrate the criticalproperties of the catalyst supports required for this invention. Themeasurements were made by subjecting the pure, thoroughly dried anddeoxygenated supports (no transition metals present) to reaction withaluminum tn'ethyl (in excess). Total gas liberated was metered,collected and analyzed. The total ethane produced is a direct measure ofthe hydroxyl group content of the support (I. Catalysis 7, 362 (1967).

The supports, after treatment with excess aluminum triethyl, were heatedin nitrogen or hydrogen at 400 F., then cooled and hydrolyzed withexcess water. Gases were metered, collected and analyzed. These gasesare a quantitative measure of the functional groups associated with thealuminum triethyl fragment (theoretically -AlEt now strongly bound tothe support. The tendency to form such groups as hydride particularly isa measure of the efficiency with which the supports function to give thecatalysts of this invention.

TABLE I.CHARACTERIZATION OF CATALYST SUPPORTS Hydroxyl groups, Fixationconditions millimols Hydride 'Iempgroups after Per erafixation Persquare ure, millimol Example Catalyst support gram meter Atmosphere F.gram A Alumina F-l 1. 68 0. 0060 Nitrogen 400 0. 12 B Alumina(alcoholate) 1. 30 0. 0064 d 400 0. Alumina (alcoholate) 1. 28 0. 0063400 0. 14

Silica (Gr. (H3) 0. 06 0. 00010 400 0. 004

nia gel 0. 24 0. 0022 400 0. l9

Activated carbon (Columbia-L) 0. 0.00008 400 0. 12

It is seen from the results given in Table I that both types ofactivated alumina and titania gel are the best supports. Silica is not auseful support'because of its very low hydroxyl content and virtually notendency 10 form hydrides. Activated carbon is not a very good supportbecause of its very low hydroxyl content although hydride groups areformed very readily at these hydroxyl sites. However, it will be shownthat the performance of activated carbon as a support for the catalystsof this invention can be enhanced by surface oxidation of the carbon.

Example 2 One hundred grams of aqueous solution was prepared bydissolving 34 grams FeCl '6H O in 66 grams of water. One hundred gramsF-1 alumina 8-14 mesh) was added to the solution and allowed to standwith occasional mixing for about 30 minutes. A small quantity of liquidwas poured off and the catalyst freed of excess liquid by placing onabsorbent paper towels. The catalyst was dried for 3 hours in a vacuumoven at 500 F. The recovered catalyst weighed 107.4 grams, and analyzed5.3 percent iron (calculated as Fe).

A heated quartz reaction tube was charged with 25.7 grams of the abovecatalyst and a preheat area above the catalyst bed was filled withstainless steel distillation packing. The catalyst was preconditioned ina stream of dry nitrogen at a temperature of 500550 F. for one hour andwas then cooled in nitrogen to room temperature. The reactor was floodedfrom the bottom with a solution of aluminum triethyl. Considerable gaswas evolved and the maximum temperature reached 200 F. After 1.33 hours,the solution was withdrawn. A rapid flow of nitrogen was introduced andthe temperature was increased to 350 F. Fixation was continued for about30 minutes.

The temperature in the catalyst bed was adjusted to 250 F. and a 20percent solution of benzene in cyclohexane was fed at a rate of about 11cc./hour and hydro gen gas at 60 cc./minute. The pressure inthe'reaction zone was essentially one atmosphere. Samples analyzed afterone hour and two hours on conditions showed no detectable benzene byvapor chromatography, all the benzene having been hydrogenated tocyclohexane.

Example 3 A catalyst prepared and activated in a manner essentiallyidentical to that described in Example 2 was used to hydrogenate a feedconsisting of percent l-hexyne in n-heptane at atmospheric pressure inthe vapor phase. The catalyst temperature was maintained at 230240 F.,the liquid fed at 11 cc./hour, and hydrogen gas at 60 cc./minute. Thel-hexyne was hydrogenated completely to n-hexane as shown by vaporchromatography and confirmed by infrared spectroscopy.

Example 4 One hundred fifty grams of F-1 activated alumina (8-14 mesh)was treated with 140 grams of an aqueous solution of 36% CoCl -6H O.After drying in vacuum for about 5 hours at 400-450 F., 162.3 grams ofintense blue catalyst was obtained. The catalyst contained 5.3% cobalt,calculated as metal.

Twenty-five grams of the above catalyst was charged to a quartz tube andpreconditioned at 700785 F. in dry nitrogen for approximately 1 hour.After cooling to room temperature in a stream of dry nitrogen, the tubewas flooded with a 20% solution of aluminum triethyl in n-heptane. Themaximum temperature in the catalyst bed reached 160 F. After about 1hour, the liquid Was withdrawn and the catalyst was fixed in a flow ofdry nitrogen at 375-400 F. for 1 hour. A 20% solution of benzene incyclohexane was fed at a rate of 11 cc./hour along with 60 cc./minute ofhydrogen. At a temperature of 216250 F. in the catalyst bed, the benzenewas completely hydrogenated to cyclohexane.

Example 5 Reagent grade magnesium oxide (50 grams) was mixed with 83grams of a 40% aqueous solution of CoCl -6H O to give a thick paste. Thepaste was spread on a glass plate and dried in a vacuum oven at 250-260F. for 3 days. The hard particle's were crushed in a mortar and 10-20mesh particles were screened out. These 1020 mesh particles were driedfor 3 hours at 425-450 F. in the vacuum oven and were light blue incolor and contained about 14 percent cobalt calculated as metal.

The quartz reaction tube was charged with 17.3 grams of the abovecatalyst which was then preconditioned in a stream of dry nitrogen at660 F. for about 30 minutes. After cooling to room temperature, the tubewas flooded with 20% aluminum triethyl in n-heptane. There was verylittle heat evolved and the liquid was withdrawn after 30 minutes. Thecatalyst was fixed in dry nitrogen at 350-365 F.

A 20% solution of benzene in cyclohexane was fed at a rate of 11cc./hour and hydrogen at a rate of 60 cc./ minute. At a catalysttemperature of 240 F., hydrogenation of the benzene was better than 99%complete.

Example 6 One hundred grams of F-l alumina was treated with grams ofcobalt octoate solution (6% cobalt dissolved in hydrocarbon vehicle) andthe solid dried in the vacuum oven. A second impregnation was carriedout in a similar manner and the vacuum dried solid amounted to 113.4

grams.

Twenty-five grams of the above catalyst was charged to the quartzreaction tube, preconditioned in N at 500 F. for 2 hours, then activatedwith 20% aluminum triethyl as previously described and fixed in nitrogenat 400 F. Only very slight hydrogenation of benzene was noted atatmospheric pressure and 240 F. Compared to Example 4, this illustratesthe advantage in catalyst activity by carrying out the originalimpregnation in an aqueous medium with water soluble salts of thetransition metal.

Example 7 The catalyst described in Example 4 was used to hydrogenateo-xylene (24% in n-heptane) at atmospheric pressure and 260270 F.Hydrogenation was complete and two isomers of dimethyl cyclohcxane wereobserved by vapor chromatography.

13 Example 8 Catalysts were prepared and evaluated by the generalprocedure described in Example 4 with the results shown 5 in Table II,Examples 8A through 8E. All the cobalt catalysts contained about 5%cobalt.

Example 11 Fifty grams of activated nickel catalyst prepared asdescribed in Example was charged to a one-liter stirred autoclave alongwith 240 ml. n-octane and 60 cc. 2-ethylhexaldehyde. Five consecutivehydrogenation runs were TABLE II Activation maximum temperature of-Benzene N2 prehydrogenacondi- AIEta tion at 1 Example Catalyst baseCobalt salt sed tioned treat atrn., 250 F,

F-lalumina None. 790 153 Notactive. B do (30304-71120 520 140 100%.

Activatedcarbon (C0lumblaearbon) COClzGHzO 520 121 77%. 8DSilicaaluminacrackingcatalyst 00011451120 500 130 77%. 8E F-laluminaCoacetatemzO 500 150 100%.

Example 9 made using the same charge of catalyst and the same volume offeed. Hydrogenation conditions and results of A catalyst consisting ofcobalt on F-l alumina was prepared from aqueous cobaltous acetateaccording to the procedure of Example 4 and contained 5.3% cobalt(calculated as metal) after drying in the vacuum oven.

The quartz tube reactor was charged with 26.1 grams of the abovecatalyst which was preconditioned at 600 F. in nitrogen for 1 /2 hours,then activated with aluminum triethyl and fixed in hydrogen at 400 F.

A 20% solution of n-butyraldehyde in n-heptane was hydrogenated atatmospheric pressure with the following results (expressed onsolvent-free basis).

A catalyst was prepared by impregnating 100 grams of 'F-l alumina with asolution prepared by dissolving 36 grams nickel acetate-4H O in 156grams water. After drying in vacuum, the catalyst was impregnated asecond time with the residual solution. After drying at 350-400 F. invacuum, 116.3 grams catalyst was recovered which analyzed 3.4% nickel(calculated as metal).

The quartz reaction tube was charged with 25.1 grams of the nickelcatalyst which was preconditioned in nitrogen at 600 F. (1 hour), thenactivated with 20% aluminum triethyl (max. temperature 125 F.) and fixedat 400 F. with dry nitrogen.

A 20% solution of C aldehyde was hydrogenated at atmospheric pressure,300400 F., 60 cc./minute hydrogen rate. Typical results obtained duringan 80-hour run were: 65

Aldehyde. n-C'r these five runs are shown below:

Hydrogenation conditions Percent Tempselecpera- Prestivitiy Percentture, sure, Time, to 2-Et. Example aldehyde F p.s.i.g. hours 1 hexanol 1Time until Hz no longer absorbed.

Example 12 A commercial cobalt modybdena on alumina catalyst containingabout 3.5% C00 and 12% M00 and in the form of inch extruded rods wascharged (36.7 grams) to the quartz reaction tube and was preconditionedin a flow of dry nitrogen at 600 F. for one hour. The catalyst had beencalcined at 1200 F. for 12 hours before charging to the tube. Aftercooling in dry nitrogen, the catalyst bed was flooded with 20% aluminumtriethyl. Maximum temperature reached was 160 F. After 40 minutes, thesolution was withdrawn and the catalyst fixed at 500 F. in a stream ofdry hydrogen for 15 minutes. After cooling, the catalyst was chargedwith 290 ml. n-octane and ml. benzene to a one-liter stirred autoclave.At a temperature of 225230 F. and a pressure of 200 p.s.i.g., thebenzene Was completely hydrogenated in 1 hour.

About ml. of the above product was left in the reactor and a freshcharge of ml. octane and 60 ml. benzene was added. This charge washydrogenated at F. and a pressure of 200 p.s.i.g. and hydrogenation wascomplete in about 1.5 hours. Selectivity to cyclohexane was essentially100%.

For comparison purposes, a hydrogen reduced platinum (0.5% Pt) onalumina catalyst used for commercial scale hydrogenation of benzene wastested under conditions identical to the second hydrogenation rundescribed above. Complete hydrogenation of benzene required 2.0 hours.

Example 13 A nickel molybdena-alumina commercial hydrotreating catalyst10-20 mesh particles size and containing 34% NiO, 14-16% M00 wasactivated with aluminum triethyl essentially as described in Example 12.

Fifty-three grams of the activated catalyst was charged to the stirredautoclave along with 240 ml. n-octane and 60 ml. benzene. Hydrogenationwas carried out at 165- 170 F. and 200 p.s.i.g. and the conversion ofthe benzene to cyclohexane was complete in 1 hour.

Example 14 A catalyst (57 grams), prepared from cobaltous acetate on F-lalumina and activated according to the procedure 15 of Example 4, wascharged to the stirred autoclave along with 240 ml. parafiinic diluentand 60 m1. trans,trans,cis- 1,5,9 cyclododecatriene. The hydrogenationconditions were 165-l70 F. and 200 p.s.i.g. Hydrogenation tocyclododecane was 96% complete in 1 hour and complete in 1.33 hours.

Example 15 Time to complete hydrogenation,

Example Support hours 15A- F-l alumina (Alcoa) 2. 03 15B F-lO alumina(Alcoa) 1.26 150 H-151 alumina (Alcoa) 3. 22 15D 471A alumina 5. 15EAlcoholate alumina- 1. 25 15F" Celite (Johns-Manville) l0. 0 15GActivated carbon (Pittsburgh Coke) 4. 75

The F-10 alumina and the alcoholate alumina were the purest aluminabases used and these gave the highest catalytic activity. Aluminascontaining 2-6% silica (H-15l and 471A) gave less active catalysts. TheCelite is largely silica and is not a useful catalyst support. The loworder of activity is probably due to formation of some cobalt metalrather than to the catalyst complexes of this invention.

Example 16 Catalysts containing 5-6% Fe on F-l alumina were preparedfrom ferric rchloride-6H O, ferrous chloride-4H O and ferric nitrate-9H0and dried in the vacuum oven. The catalysts were preconditioned at 800F. in dry nitrogen and then contacted with aluminum triethyl at roomtemperature (maximum temperature during activation was about 200 F.) Thecatalysts were treated in nitrogen at 400 F. for fixation. Samples weretaken after the 800 F. N preconditioning and after the final 400 F. Nfixation for examination by Mossbauer spectrometry to determine thevalence lstate of rtihe iron, and for correlation with catalyticactivity. The results obtained were as follows:

The 10-20 mesh catalyst was charged to a heated quartz tube,preconditioned at 600 F. for one hour in a nitrogen atmosphere, thenactivated with aluminum triethyl and then fixed in nitrogen at 400 F. I

The above catalyst grams) was mixed with 250 ml. isooctane and 50 m1.benzene in a one-liter autoclave and the hydrogenation of the benzenewas complete in 5.2 hours at 165 F. and 200 p.s.i.g.

Example 18 These examples show that magnetic susceptibility measurementson typical catalysts of this invention confirm that the Group VIIInonnoble metals are present in the +2 valence state. All catalysts wereprepared on F-l alumina base and, containing 46%' equivalent metal, wereactivated in the liquid phase with triethyl aluminum (20%solution),-then fixed in a nitrogen atmosphere at 400 F. The ironcatalysts derived from FeCl and Fe(NO were the same catalysts in whichthe Mossbauer meaurements described in Example 16 were made.

Literature values are for these elements in octahedral configurmation.For the iron catalysts, the values are in good agreement forpredominantly an Fe+ configuration but containing a small amount of Fe+contaminant (as shown by the Mossbauer data in Example 16). Only in thecase of the catalyst derived from Fe(NO was a minute trace (about 85ppm.) of metallic iron detected.

The nickel and cobalt catalysts (Ni+ and Co+ salts used in preparation)are in fairly good agreement but slightly lower in magnetic moment thanthe literature values. It is well known that distorted configurationssuch as would exist on a support surface will lower the magnetic moment.

Example 19 A catalyst containing 6.5 weight percent iron was prepared byimpregnating an alcoholate type alumina with 1 Catalyst not active at165 F., 200 p.s.i.g., but benzene hydrogenation was complete in 1.8hours at 800 F., 400 p.s.i.g. The catalysts pre ared from chloride hadhigh activity and high concentrations of Fe+ in the final activate(fixed) state while the catalyst prepared from nitrate had a much lowerorder of activity and a much lower concentration of Fe.

N o metallic iron was detectable.

Example 17 Zinc oxide (442 grams) was mixed with a solution of 93.5grams nickel acetate-4H O in 450 ml. warm water to give a thick paste.The mixture was dried in the vacuum oven giving chucks of greenish-whitesolid. The solid was broken in a mortar and screened at 10-20 mesh size.

aqueous iron nitrate. In the following table the benzene hydrogenationactivity of this catalyst, activated in accordance with this invention(preconditioned at 800 F. in N and fixed as indicated), is compared withthe activity of the same catalyst activated by severe hydrogen treating.

l 6.5% Fe on PF alumina.

The catalyst activated by hydrogen alone is essentially inactive forbenzene hydrogenation (at 212 F., 600 p.s.i.g.). There are only slightdiiferences in activiity between the mildly fixed (400 F.) and severelyfixed (1200 F.) catalysts. The Mossbauer results (presence of alphairon) indicate that this catalyst contained too high an ironconcentration for maximum activity and complete stabilization.

Example 20 A catalyst similar to that of Example 19 was prepared fromiron nitrate on the same alumina base, except that the iron content was3.2 wt. percent. This catalyst was activated according to the procedureused for Example 19B, activity for benzene hydrogenation was 0.04 mol/hr./gm. Fe at 212 F. and 0.38 mol/hr./gm. 'Fe at 300 F. The same chargeof catalyst was placed back in the tube and heated in hydrogen for 16hours at 1200 F. The

hydrogenation activity tests were repeated. At 212 F.

the activity was 0.54 mol/ hr./ gm. Fe and at 300 F. was 2.4 mol/hr./gm.Fe. At this more optimum iron concentration and more optimum Al/Feratio, the stabilization of the iron by the aluminum is much morecomplete and the activity is enhanced on the order of tenfold or more.Example 21 A series of iron catalysts containing 0.8, 1.6, 3.2 and 6.4percent Fe were prepared on the alcoholate type alumina base. The basecontains 1.2 millimols/gm. CH group equivalent and the Fe wasimpregnated on the base as FeCl -6H O. The catalysts were activated bypreconditioning at 600 F. (N atmosphere), treating with 20 percent Al'Etin n-heptane, then fixed in hydrogen at 400 F. Activities weredetermined on an absolute basis (mols benzene hydrogenated per hour pergram Fe) in a standard hydrogenation test at 212 F. and 600 p.s.i. Hpressure. Results of these tests were:

Hydrogenation rate, mol./hr./gm. ole Fe ratio,

Fe/OH 212 F. 300 F.

The results are very striking in showing the critical effect oftransition metal/hydroxyl group ratio in preparing these catalysts.There is a fairly sharp maximum in catalytic activity occurring at anFe/O'H molar ratio of about 0.5. However, even at the greatly nonoptimumratio of 0.12, the activity of catalyst is increased more than six-foldby increasing the temperature to 300 F.

Example 22 This example is to show the positive identification of Fe-Allinkages in high activity iron catalysts prepared according to thisinvention. Also, it is designed to show the amount of iron present inthe active catalytiestate. The method is based on hydrolysis of theactivated, fixed l8 catalysts with deuterium oxide, and that (1) hydridegroups on Al or Fe will give HD on deuterolysis, and (2) --Al-Fe directlinkages will give D on deuterolysis. Thus the D make will be a directmeasure of Al-Fe groups. The two most active catalysts from Example 21(6.4% Fe and 3.2% Fe preconditioned at 600 F.) were used in these tests.All gases liberated during the treat with 20% AlEt during the hydrogenfixation and during the denterolysis with excess D 0 were metered,collected and analyzed. The deuterolysis gases were analyzed for HD, Dand deuterated components of methane and ethane in addition to the usualcomponents. Results of these exhaustive tests for the two iron catalystswere:

Example- 22A 22B Catalyst, weight percent, Fe 6. 4 3. 2 Totaldeuterolysis gas, mInoL/gm. catalyst 1. 62 1. 78 D: made, mmoL/gm.catalyst 0. 41 0. 34 HD made, mmol./gm. catalyst- 0. 34 0. 89 Du, molepercent on Fe 36 59 Hydrogenation activity, mol./hr./gm. Fe 1. 94 2. 60

The D concentration expressed as mol percent on Fe represents thepercent of iron as the catalytically active species, that is, having anaverage of one iron to aluminum direct chemical bonds. The catalystbonding the greater percent iron in this form is the same as thecatalyst of Example 21, Run B.

Example 23 Absolute hydro- Precondigenation tioning rate,temperamol./hr./ Example ture, F. gm. Fe

These results show clearly that an inferior catalyst results at lowpretreat temperatures. At the highest temperature, 900 F., somecrystallite growth may have occurred since the high stabilitycharacteristic of these catalysts is not realized prior to the alkyltreat and fixation in the presence of hydrogen.

Example 24 A catalyst containing 6.5% Fe was prepared by impregnatingsilica gel (Davison Grade 0-8) with FeCl aqueous solution. The catalystwas preconditioned at 800 F., treated with 20% AlEt solution, then fixedin hydrogen at 400 F. Activity for benzene hydrogenation was notmeasurable at 212 F. and was on the order of 0.002

.mol./hr./ gm. Feat 300 F. This silica-based catalyst is essentiallyinactive because any hydroxyl groups in the silica base undergoalkylation to give SiEt groups rather than the necessary --Si-O-- AlEtgroups.

Example 25 This example is designed to show the importance of hydroxylfunctionality on a support such as activated carbon. Colombia activatedcarbon Grade L (surface area 1350 sq. in./ gm.) was impregnated with anaqueous solution of ferric chloride to give 6.0 wt. percent Fe. Another7 sample of the carbon was air-oxidized at 500 F. for 16 hours and thenimpregnated to give 6% Fe. Both catalysts were preconditioned for 2 hrs.at 600 F. in N atmosphere,'treated with triethyl aluminum (20%solution),

- 19 7 then fixed in hydrogen for 1 hour at 400'? F. Benzenehydrogenation activities were as follows for these catalysts.

Hydrogenation activity, mol./hr./gm. Fe

Carbon Carbon base not base Benzene hydrogenpreoxpreexation temperature,F. idizcd idized Example 26 A titania gel base having a surface area of106-'sq. meters/gm. was determined to have a hydroxyl group content of0.24 millimol/ gm. as described in Example 1. This base (100 grams) wasimpregnated with a solution prepared by dissolving 17 gms. FeCl -6H O insuflicient water to give 65 cc. of solution. Essentially all thesolution was absorbed and the iron content of the catalyst was 3.2 wt.percent after drying in the vacuum oven.

A 50cc. portion of the catalyst was activated as follows: (a)preconditioned at 600 F. for 2 hours in a flow of dry nitrogen ;(b)treated with an excess of 20% AlEt solutionmaximum temperature was 192F.; and (3) fixation in hydrogen for one hour at 400 F.

The activatedcatalyst (5 6.4 gms.) was charged with 250 cc. of benzeneto the stirred autoclave and a hydrogenation test carried out at 212 F.and 600 p.s.i.g. H pressure. The hydrogenation was complete in 1 /2hours and the catalytic activity calculated to'be 1.03 mol./hr./ gm. Fe.

Example 27 The iron catalyst containing 3.2% Fe derived from nitrate onthe alcoholate alumina base was activated with diethyl zinc and triethylboron in comparison with triethyl aluminum. The catalyst preconditioningactivation and fixation conditions and hydrogenation activities were asshown in the table below:

Example 27A 27B 27C Alkyl used AlEt; BEt; ZnEt, Preconditioningtemperature, F 600 600 600 Alkyl treat, temperature F. (maximum). 200650 190 Fixation (H2 atmosphere Temperature, F 400 400 1, 200

Time, hours 1 1 16 Hydrogenation activity, in 0. 38 0. 031 0. 11 Attemperature, F 300 392 392 Example 28 A catalyst having a very lownickel concentration (0.6 wt. percent Ni) was prepared by impregnatingthe alcoholate alumina base with an aqueous solution of nickelousacetate. Hydrogenation activities for activation with hydrogen alone andby the method of this invention are compared in the table.

The noble metals of Group VIII are also converted to highly active andstable catalyst by the technique of this invention. However, the noblemetals, because of cost and activity considerations, are generally usedin very low concentrations, e.g., 0.1/ 1.0%, onv the support..With.,theusual supports, this results in very high alkylmetal' tonoble metalmolar ratios (e. g. 20/1 to /1). Under such conditions and at mildfixation severity, the noble metal may be overwhelmed or buried by thealkyl'metal resulting in low catalyst activity. But it has been foundvthat at very severe fixation conditions this effect is overcome andhighly active and extremely stable catalysts result.

A 0.6% platinum on alcoholate alumina was prepared by impregnation withaqueous chloroplatinic acid. The activity of this catalyst at severalseverities of hydrogen activation was as follows:

Example 29A 29B 29C Catalyst H reduction condition:

Temperature, F 800 1, 200 1, 200 Time, hours 2. 5 2. 5 18. 5 Time, hoursto completion 0. 90 1. 33 1. 75 Absolute hydrogen activity 22. 8 18. 0l2. 2

1 0.6% Pt. on alcoholate alumina. Mol./hr./gm. Pt. i

The decreasing activity with increasing severity of hydrogen reductionis attributed to growth of larger crystallites of platinum metal. Itwas, however, not possible to detect this by X-ray at this low platinumconcentration.

Example 29D 29E 7 29F 29G Catalyst (l 400 300 1,200 1, 200 1 2. 5 16 32Time, hours to completion 53 15. 8 1. 6 0.67 Absolute hydrogen activitymol./hr./

gm. Pt 0. 37 1:40 11. 8 17. 2

0.6% Pt on alcoholate alumina. 1 Standard.

Example 30 A molybdenum catalyst containing 13 wt. percent M00 wasprepared by'impregnating 200' grams of the alcoholate alumina base witha solution of 38 grams ammonium molybdate (82% M00 dissolved in cc.water. All liquid was absorbed and the catalyst was dried in the vacuumoven.

A 50 cc. portion of this catalyst was charged to the quartz tube andheated in a flow of dry nitrogen at 800 F. for 2 hours. After cooling toroom temperature, the catalyst was treated with 20% triethyl aluminumgiving a transient maximum temperature of F. After one hour, the liquidwas withdrawn and the catalyst was fixed in hydrogen at 400 F. for 1%hours.

Thirty-nine grams of the activated catalyst and 250 cc. of benzene werecharged to a stirred autoclave and a hydrogenation was carried out at212 F. and 600 p.s.i.g. H pressure. The reaction was complete in 3 hoursand the calculated rate of hydrogenation was 0.28 mol benzenehydrogenated per hour per gram of molybdenum.

Example 31 In the data tabulated below, the 13% M00 on alcoholatealumina catalyst is used to show the effects of (1) Hydrogenactivationvs. the activation method of this invention.

11(2), Increasing severity of fixation in a hydrogen atmosp ere.

21 (3) Fixation in hydrogen compared to fixation in nitrogen at highseverity.

(4) The activation method of this invention in inhibiting formation oflarge crystallites of transition metals (free metals).

22 Example 33 The results tabulated below were obtained with twotungsten catalysts on alcoholate type alumina having respective tungstenconcentrations of 27 percent W and Example 31A 81B 31C 31D 31E 31FCatalyst activation, AlEta treat None None Standard treat Fixation:

Atmosphere Nitrogen Temperature, F 1, 200 1, 200 400 900 1, 200 800Time, hours. 16 44 1 16 16 16 Hours to completio 69 91 3. 3 1. 83 1.606. 6 Absolute hydrogen act 0. 012 0. 0096 0. 27 0. 42 0. 53 0. 12Relative Mo metal 0. 69 l. 00 0. 000 0. 036 0. 012

B Catalyst heated at 800 F. in N2 AlEt; at room temperature.

b Hydrogen.

0 Mols benzene hydrogenated per hour per gram of metal.

' By X-ray difiraction, relative values based on most severely reducedcatalyst.=l.00.

Examples 310, D and E show the efiects of increasing severity offixation in the presence of hydrogen.

Examples 31C, D, and E, in comparison with Ex- 9 percent WO Theseresults will show the effects of the concentration of the transitionmetal, in this case, tungsten.

1 Most metal also W0; and W30 W W O gwao. 1 No crystallite forms of Wmetal or oxides.

3 W metal possibly W0; and W 0.

4 No W metal possible small concentration W02. No W metal less W02 thanEx. 33D.

amples 31A and B, show the activation method of this invention incomparison with hydrogen activation. The X-ray diifraction data forthese runs show how the technique of this invention stabilizes theactive catalytic species in a very stable, highly dispersed form.

Examples 31D and F show the efiects of fixation in nitrogen compared tofixation in hydrogen and that the presence of hydrogen during fixationresults in a significant increase in the hydrogenation activity of thecatalyst.

Example 32 A catalyst containing about wt. percent tungsten was preparedby impregnating 200 gms. of alcoholate type alumina with an aqueoussolution prepared by dissolving 31 grams of ammonium meta tungstate in110 cc. water. All solution was taken up.

A 50 cc. portion of the above catalyst was changed to an electricallyheated quartz tube and heated at 850 F. in a flow of dry nitrogen for 3hours.

After cooling to room temperature, the catalyst bed was flooded from thebottom with a solution of triethyl aluminum in n-heptane. Thetemperature rose transiently to 190 F. and much gas was evolved. Afterminutes the solution was drained oif and the catalyst was then heated innitrogen at 400-420" F for one hour.

I Forty grams of the above catalyst and 250 cc. benzene were charged toa stirred autoclave and a hydrogenation was carried out at 212 F. and600 p.s.i.g. H pressure. Gas was absorbed at a rate of 20 lbs. perminute and the reaction was complete in 4.1 hours. The absolute rate ofhydrogenation was calculated to be 0.17 mole of benzene hydrogenated perhour per gram of tungsten.

Another run made with the same catalyst at 260 F. gave'a hydrogenationrate of 0.31 mol/hr./gm. of tungsten.

Examples 33A, B and C with the high tungsten concentration show that theAlEt activated, hydrogen fixed catalyst (Example 333) is more than 50times as active as the catalyst activated by hydrogen (Example 33A).However, this catalyst is unstable at higher severity hydrogen fixation.The Al/W ratio (Al from AlEt is insufiicient to stabilize this amount oftungsten.

The Al/W ratio is much more favorable at the 9% W0 concentration andmost of the tungsten is stabilized, does not undergo crystallite growth,and activity remains constant as fixation severity is increased (compareExample 33F with Example 33E).

Example 34 Results obtained at a still lower tungsten concentration (6%W0 on the alcoholate alumina base) show a striking enhancement inactivity as fixation severity is increased.

This catalyst, when given the standard AlEt activation (as in Example33) and fixed in hydrogen for 1 hour at 400 F., had a benzenehydrogenation activity of 0.10 mol/hrJgm. W. The same catalyst was thenplaced back in the activation tube and given an additional fixation of16 hours at 1200 F. in hydrogen. This catalyst then showed an activityof 0.71 mol/hr./gm. W. This high activity is now completely stabilized.

Example 35 A catalyst was prepared by impregnating 200 gms. of F-lalumina with a solution of 3 ml. perrhenic acid (1.3 gms. Re/ml.) madeup to ml. with water. All solution was absorbed. Catalyst was dried inthe vacuum oven and had a rhenium content of 2.0 wt. percent.

The quartz activation tube was charged with 55 cc. of the above catalystand heated in a flow of dry nitrogen at 600 F. for 2 hours. Aftercooling to room temperature, the catalyst bed was Lflooded from thebottom with a 20% solution of aluminum triethyl. The maximum temperaturereached 210 F. After one hour, the solution was drained off and thecatalyst was fixed in hydrogen for one hour at'400* F.

The stirred autoclave was charged with 51.5 gms. of the above catalystand 250 cc. of a 20% solution of benzene in n-octane.

At a temperature of 260 F. and a hydrogen pressure of 500 p.s.i.g., thebenzene was hydrogenated at a rate of 0.22 mol/hr./gm. Re.

Example 36 A catalyst was prepared by impregnating 200 gms. F-l aluminawith a solution prepared by dissolving 40 gms. CrO in sufiicient waterto give a total volume of 125 ml. All liquid was absorbed. The catalystwas dried in the vacuum oven and the chromium content was 9 wt.

percent. 1

The catalyst (60 cc.) was activated as follows: (1) heated in air for 16hours at 1000 F.; (2) heated in dry nitrogen for 1 hour at 100Q F.; (3)cooled to room temperature and treated with an excess of aluminumtriethyl (20% solution), maximum temperature reaching 240 F.; and (4)finally treating in'hydrogen for 2 hours at 400 F.

The activated catalyst (49- gms.) was charged to the stirred autoclavewith 250 cc. benzene. Hydrogenation at 300 F. and 600 p.s.i.g. Hpressure gave a measured reaction rate of 0.062 mol of benzenehydrogenated per hour per gram of chromium.

Example 37 A catalyst was prepared by impregnating 200 gms. ofalcoholate type alumina with a solution of 38 gms. ammonium vanadatedissolved in a mixture of '80 cc. of water and 60 cc. ofmonoethanolamine, the latter added to aid in dissolving the ammoniumvanadate. After drying in the vacuum oven, the catalyst contained 7.5%vanadium.

The catalyst was activated as follows: (1) heated in air for 7 /2 hoursat 1000 F.; (2) heated in dry nitrogen for 1 hour at 800 F.; (3) cooledto room temperature.

and treated with an excess of aluminum triethyl (20% solution), maximumtemperature reaching 205 F.; and (4) fixation in hydrogen at 400 F. for1 hour.

The activated catalyst (41 gms.) was charged to the autoclave with 250cc. of benzene. Hydrogenation at 212 F. and 600 p.s.i.g. H pressure gavea hydrogenation rate of 0.08 mol/hr./gm. vanadium and at 300 F. and 600p.s.i.g. the rate increased to 0.21 mol/hr./ gm.

Example 38 A catalyst containing 6 wt. percent copper was prepared byimpregnating 200 gms. F-l alumina with a solution prepared by dissolving34 gms. CuCl 2H O in sufiicient water to give 160 cc. solution. Allsolution was absorbed and the catalyst was dried in the vacuum oven.

The activation tube was charged with 47.2 gms. of the catalyst, theweight being determined after preconditioning the catalyst at 800 F. for2 hours in dry nitrogen. The catalyst was then activated with an excessof aluminum triethyl and fixed in hydrogen at 400 F. for one hour.

The fixed catalyst was then hydrolyzed with deuterium oxide and gasesevolved were collected and analyzed. The gases were principally C2H D, Dand HD, the latter two components amounting to 0.18 and 0.07 millimolper gram of catalyst, respectively. This amount of D corresponds to 19percent of the copper bonded directly to aluminum and an average of 4mol percent bydride (based on copper) associated with the copperaluminumcomplex.

24 This catalyst had relatively low activity for hydrogenation ofbenzene, .the activity being determined as 0.033 mol/hr./gm. Cu at 392F. and 600 p.s.i.g. H

pressure.

Example 39 A catalyst containing 6 wt. percent manganese was prepared byimpregnating 200 gms. of -alcoholate alumina with a solution prepared bydissolving 54 gms. manganous acetate (4 H O) in sufiicient water to give225 cc. of solution. Essentially all liquid was absorbed and thecatalyst was dried in the vacuum oven.

A 50 cc. portion of the catalyst was placed in the heated quartz tubeand preconditioned at 800 F. in a flow of dry nitrogen for 2 hours. Thetemperature was then reduced to 400 F. and aluminum triethyl (20%)solution was added dropwise over a period of one hour. The temperaturemaximum was 565 F. After one hour the alkyl solution was cut off and thecatalyst was fixed at 400 F. in a stream of dry hydrogen.

Thirty-six grams of the activated catalyst was charged to the stirredautoclave with 250 cc. benzene. At 392 F. and 600 p.s.i.g. H pressure,the hydrogenation rate was 0.015 mol/hr./gm. Mn.

Example 40 A catalyst containing about 7 wt. percent nickel was preparedby three consecutive impregnations of 500 gms. F-l alumina withsolutions containing 50 gms. nickel acetate (-4H O) in sufiicient waterto give 250 cc. solution. The catalyst was dried in the vacuum ovenbetween impregnations.

The activation tube was charged with 50 cc. of this catalyst which waspreconditioned by heating at 800 F. for 2 hours in a flow of drynitrogen. After cooling to room temperature, the catalyst was treatedwith an excess of a 20% solution of diethyl aluminum fluoride innheptane. After standing for about 1 hour, the solution was drawn 0E andthe catalyst was fixed in a flow of dry nitrogen at 400 F. for 1 hour.The catalyst was analyzed and contained 6.4% nickel and 2.5% fluorine.

The stirred autoclave was charged with 43.4 gms. of the above activatedcatalyst and 250 cc. of benzene and a hydrogenation reaction was carriedout at 212 F. and 600 p.s.i.g. H pressure. The hydrogenation rate of thebenzene was 0.39 mol/hr./ gm. Ni.

What is claimed is: 1. A process for forming a hydrogenation catalystwhich comprises:

impregnating a support containing at least 0.1 millimol of hydroxylgroups per gram of support with an aqueous solution of a salt of atransition metal wherein the transition metal is selected from the groupconsisting of Group I-B, IV-B, V-B, VI-B, VII-B, and Group VIII metalsand mixtures thereof;

heat-treating the impregnated support at a temperature of at least about500 F. to remove liquid and adsorbed oxygen;

activating the heat-treated impregnated support by contacting same witha predominantly co-valently bonded organometallic compound having theformula: QR wherein Q is selected from Groups I, II

or III metals of the Periodic Chart of the Elements, R is selected fromthe group consisting of hydride and, alkyl, aryl, alkaryl, aralkyl orcycloalkyl radicals containing from 1 to about 20 carbon atoms andwhereinn ranges from 1 to 3 and satisfies the valence of Q; andthereafter treating the activated supported metal complex in thepresence of hydrogen at a temperature of at least about 300 F. 2.,Theprocess of claim 1 wherein the support is selected from oxides of GroupsII, III and IV of the Periodic Chart of the Elements.

3. The process of claim 1 wherein Q has an atomic number of from 3 to 50and wherein QR is a trialkyl aluminum.

4. The process of claim 1 wherein the activated supported metal complexis treated in the presence of hydrogen at a temperature above 800 F.

5. The process for forming a hydrogenation catalyst which comprises:

impregnating a support having a surface area of at least 5 square metersper gram and containing at least 0.1 millimole of hydroxyl groups pergram of support with an aqueous solution of a salt of a transition metalwherein said transition metal is selected from the group consisting ofGroup I-B, IV-B, V-B, VI-B, VII-B, and Group VIII metals and mixturesthereof;

heat-treating the impregnated support at a temperature of at least about500 F. to remove liquid and adsorbed oxygen;

activating the heat-treated impregnated support by contacting same witha predominantly co-valently bonded organometallic compound having theformula: QR wherein Q is selected from Groups I, II and III metals ofthe Periodic Chart of the Elements having an atomic number of from 3 to50, R is selected from the group consisting of hydride and, alkyl, aryl,alkaryl, aralkyl and cycloalkyl radicals and wherein n ranges from 1 to3 and satisfies the valence of Q; and

thereafter heating the activated supported metal complex in the presenceof a gaseous stream containing hydrogen at a temperature of at leastabout 300 F.

6. The process of claim 5 wherein the support is selected from oxides ofGroups II, III and IV of the Periodic Chart of the Elements.

7. The process of claim 5 wherein the amount of transition metalimpregnated on the support is in the range of from about 0.1% to about30% based on the total weight of the deposited equivalent metal andsupport.

8. The process of claim 5 wherein the impregnated support isheat-treated in an inert atmosphere at a temperature in the range offrom about 600 to about 15 F.

9. The process of claim wherein the heat-treated impregnated support isactivated by contacting same with a hydrocarbon solution of a tri-alkylaluminum wherein the alkyl groups contain from 1 to about 6 carbonatoms.

10. The process of claim 5 wherein the activated supported metal complexis treated in the presence of a gaseous stream containing hydrogen at atemperature in the range of from about 400 to about 1200 F.

11. The process of claim 10 wherein the amount of hydrogen in thegaseous stream is in the range of from about 75% to about 100%. I

12. A process, for forming a hydrogenation catalyst which comprises:

impregnating a support having a surface area of at least 5 square metersper gram and containing at least 0.1 millimole of hydroxyl groups pergram of support with an aqueous solution of a salt of a transition metalselected from Groups I-B, IV-B, V-B, VI-B, VII-B and Group VIII metals;

heat-treating the impregnated support in an inert atmosphere at atemperature in the range of from about 600 to about 1500 F.;

activating the heat-treated impregnated support by contacting same witha hydrocarbon soluble trialkyl aluminum compound wherein the alkylgroups have from 1 to about 6 carbon atoms; and

thereafter treating the activated supported metal complex in thepresence of hydrogen at a temperature of at least about 300 F.

13. The process of claim 12 wherein the support is selected from theoxides of Groups II, IH and IV of the Periodic Chart of the Elements.

14. The process of claim 13 wherein the support has a surface area of atleast 50 square meters per gram and a hydroxyl group content of at leastabout 0.2 millimole of hydroxyl groups per gram of support.

15. The process of claim 14 wherein the support is an aluminum oxidehaving a surface area of above about 100 square meters per gram and ahydroxyl content of at least one millimole per gram of support.

16. The process of claim 15 wherein the support is impregnated with anaqueous salt of a transition metal selected from the group consisting ofiron, cobalt, nickel, platinum, tungsten, chromium, molybdenum,vanadium, rheni-um, copper, and mixtures thereof.

17. The process of claim 16 wherein the impregnated support isheat-treated at a temperature in the range of from about 600 to about1000 F.

18. The process of claim 17 wherein the amount of trialkyl aluminumcompound in the hydrocarbon diluent is in the range of from about 5 toabout 50%.

19. The process of claim 18 wherein the activated supported metalcomplex is heated in the presence of a gaseous stream containinghydrogen at a temperature ranging from about 400 F. to about 1200 F.

20. The process of claim 19 wherein the activated supported material istreated in the presence of a gasous stream containing from about toabout hydrogen at a temperature in the range of from about 800 to about1200 F.

21. The process of claim 20 wherein the activated supported metalcomplex is treated in a 100% hydrogen atmosphere.

References Cited UNITED STATES PATENTS 3,113,931 12/1963 Voltz 252-4423,288,725 11/ 1966 Aftandilian 252-447 3,415,759 12/1968 Johnson 252-4553,536,632 10/1970 Kroll 252-430 3,205,178 9/ 1965 Orzechowski 23-4293,221,002 11/ 1965 Orzechowski 260-949 DANIEL E. WYMAN, Primary ExaminerP. M. FRENCH, Assistant Examiner U.S. Cl. X.R. 252-430, 429, 428

